.bigBox {
  position: relative;
  width: 500px;
  height: 226px;
  margin: 150px;
}

.left {
  position: absolute;
  z-index: 1000;
  top: 100px;
  left: 0;
  color: white;
  background-color: rgba(0, 0, 0, .3);
  font-size: 30px;
  cursor: pointer;
}
.right {
  position: absolute;
  z-index: 1000;
  background-color: rgba(0, 0, 0, .3);
  top: 100px;
  font-size: 30px;
  color: white;
  right: 0;
  cursor: pointer;
}
.right:hover{
  background-color: rgba(0, 0, 0, .8);
}
.left:hover{
  background-color: rgba(0, 0, 0, .8);
}
img{
  position: absolute;
  top: 0;
  width: 500px;
}

li{
  list-style: none;
  background-color: #fff;
  border-radius: 50%;
  margin: 0 5px;
  width: 14px;
  height: 14px;
  float: left;
  cursor: pointer;
}

ul{
  position: absolute;
  background-color: rgba(0, 0, 0, .3);
  bottom: 0px;
  left: 200px;
  padding: 10px;
  border-radius: 8px;
  z-index: 1000;
}

.active{
  background:red;
}